Epoxidation of olefin compounds, like epoxidation of propylene to give propylene oxide, has been well known in the art, where an oxygen-donating agent of alkyl hydroperoxide and a homogeneous molybdenum catalyst or a heterogeneous titanium/silica catalyst are essentially required.
Sherrington and Simpson-discloses a supported metal catalyst by impregnating polystyrene resin with molybdenum and vanadium catalyst(see: Sherrington D. C. and Simpson S., Journal of Catalysis, 131:115-126, 1991). Miller and Sherrington also teaches a molybdenum(VI) catalyst impregnated in a heat-resistant polymer of polybenzimidazole which is employed in the epoxidation of cyclohexene(see: Miller M. and Sherrington D. C., Journal of Catalysis, 152:377-383, 1995).
Comparative study on the said two catalysts has revealed that: the catalyst impregnated in a heat-resistant polymer of polybenzimidazole has a catalytic activity and stability better than that of polystyrene-supported catalyst; and, the stability of the said two catalysts significantly decreases in the epoxidation of higher olefins.
In addition, U.S. Pat. No. 5,420,313 discloses an epoxidation of olefin by a molybdenum catalyst impregnated in polybenzimidazole resin, where the catalyst showed excellent catalytic activity and selectivity in the course of preparing propylene oxide from propylene, and retained catalytic activity on recycling without leaching. The catalyst, however, has revealed several shortcomings as follows: First, its catalytic activity decreased gradually, when it is recycled in the epoxidation of a higher olefin such as cyclohexene; Secondly, the polybenzinidazole resin employed as a support can only be prepared by a complicate melting process at a high temperature over 200.degree. C.; Thirdly, the monomer used for preparing the polybenzimidazole resin is very expensive.
Therefore, there are strong reasons for developing a novel supported catalyst which has a high catalytic activity and selectivity in the epoxidation of higher olefin and retains its activity after repeated use, by employing an inexpensive heat-resistant polymer support.